As illustrated in FIG. 1, FIG. 1 is a top view of a display device in the prior art. Existing display device 10′ mainly includes a display region 2′ formed on a substrate 1′ and arranged with pixels, a driving circuit 3′ and a packaging region 4′. The packaging region 4′ surrounds the display region 2′, and the driving circuit 3′ is disposed between the packaging region 4′ and the display region 2′.
As illustrated in FIG. 2, FIG. 2 is a cross sectional view alone line E-E of FIG. 1. A portion A in FIG. 2 represents a schematic cross sectional view among the display region 2′, the driving circuit 3′ and the packaging region 4′, and a portion B represents a schematic cross sectional view of the display region 2′. The substrate 1′ includes the display region 2′. The driving circuit 3′ is formed at a vicinity of the display region 2′. A passivation layer 5′ covers the driving circuit 3′ and includes a contact hole exposing the driving circuit 3′. A display element is formed in the display region 2′, and the display element includes at least a cathode 6′, a driving element layer 7′, a pixel defining layer 8′ and an organic light emitting layer 9. The cathode 6′ extends from the display region 2′ to the driving circuit 3′, and is electrically connected to the driving circuit 3′ through the contact hole. The display device 10 is an active-matrix organic light emitting diode (AMOLED) panel, and the driving element layer 7′ further includes elements such as a TFT driving element, an anode, or the like.
In the display device 10′, an edge of the cathode 6′ extends far beyond the display region 2′, and the conduction and connection between the cathode 6′ and the lower layer circuit (i.e., the driving circuit 3′) are formed at the beyond portion which is positioned over the driving circuit. A distance h by which the cathode 6′ extends beyond the display region 2′ is greater than 70%, or even 80% of a width H of the driving circuit 3′. Here, a thickness of the cathode 6′ may be 150 Å.
Accordingly, film quality in this region has direct influence on the narrow bezel. As illustrated in FIG. 3, FIG. 3 is a schematic diagram of a state of vapor deposition of the display device in the prior art. The display device 10′ is disposed on a mask 12′ over an evaporation source 13′, and the evaporation source 13′ forms the cathode (not illustrated in the drawing) by vapor deposition process. Since it is difficult to control a boundary of the vapor deposition process, edges of the formed film may have a relative larger displacement. Accordingly, if the edge is offset to the package region 4′, the packaging effect may be influenced, and if the edge is offset to the display region 2′, the display device 10′ may display abnormally due to bad connection. Thus, the distance between the package region 4′ and the display region 2′ is generally kept sufficiently large. Particularly, when the driving circuit 3′ may be reduced to be very small, such a distance is still required to be kept sufficiently large. This is extremely disadvantageous to the narrow bezel of the display panel.